/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package com.aliyun.odps.cupid.table.v1.util;

import com.aliyun.odps.cupid.table.v1.Attribute;
import java.util.Arrays;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

public abstract class Schema implements Iterable<Attribute> {

    public int size() {
        return columns.length;
    }

    public Attribute get(int index) {
        return columns[index];
    }

    public Attribute[] toArray() {
        return columns.clone();
    }

    public List<Attribute> toList() {
        return listView;
    }

    private Attribute[] columns;

    private List<Attribute> listView;

    protected Schema(Attribute[] columns) {
        this.columns = columns;
        this.listView = Collections.unmodifiableList(Arrays.asList(columns));
    }

    @Override
    public Iterator<Attribute> iterator() {
        return listView.iterator();
    }
}
